use separate build directory for rust-analyzer to use

[tshepang]

Proposal

To avoid the issue of locking between normal builds and rust-analyzer builds, we should set the in-tree rust-analyzer settings (accessible via x setup editor) to make rust-analyzer use a build directory separate from the one used by bootstrap.

In addition to that, it would be good to decide on the following 2 options:

• Use build/rust-analyzer/ (currently used by Helix settings)

  The benefit is that we don't have to add another top-level directory.

• Use build-rust-analyzer/

  The benefit is that x clean --all does not also remove rust-analyzer build artefacts
  (because "build/" belongs to bootstrap, probably).

  make rust-analyzer use a dedicated build directory rust#141839 follows this approach.

Process

The main points of the Major Change Process are as follows:

• File an issue describing the proposal.
• A compiler team member or contributor who is knowledgeable in the area can second by writing @rustbot second.
  • Finding a "second" suffices for internal changes. If however, you are proposing a new public-facing feature, such as a -C flag, then full team check-off is required.
  • Compiler team members can initiate a check-off via @rfcbot fcp merge on either the MCP or the PR.
• Once an MCP is seconded, the Final Comment Period begins. If no objections are raised after 10 days, the MCP is considered approved.

You can read more about Major Change Proposals on forge.

[rustbot]

Important

This issue is not meant to be used for technical discussion. There is a Zulip stream for that.
Use this issue to leave procedural comments, such as volunteering to review, indicating that you second the proposal (or third, etc), or raising a concern that you would like to be addressed.

Concerns or objections can formally be registered here by adding a comment.

@rustbot concern reason-for-concern
<description of the concern>

Concerns can be lifted with:

@rustbot resolve reason-for-concern

See documentation at https://forge.rust-lang.org

cc @rust-lang/compiler

[jieyouxu]

@rustbot second

[rustbot]

The final comment period is now complete, this major change is now accepted.

As the automated representative, I would like to thank the author for their work and everyone else who contributed to this major change proposal.

If you think this major change shouldn't have been accepted, feel free to remove the major-change-accepted label and reopen this issue.